Generally, silver halide photographic materials have a layer containing a hydrophilic colloid, such as gelatin, as a binder on at least one side of a support. The hydrophilic colloid layer has the disadvantage that it is liable to be expanded or contracted by changes in humidity and temperature.
The dimensional change of the photographic materials due to the expansion and contraction of the hydrophilic colloid layer is a very serious problem in the field of printing photographic materials which must reproduce accurately line drawings or halftone dot images for multi-color printing
U.S. Pat. No. 3,201,250 discloses a method wherein the ratio of the hydrophilic colloid layer to the support is specified for photographic materials that have excellent dimensional stability. The incorporation of a polymer latex in the hydrophilic colloid layer is described in Nos. JP-B-39-4272 (the term "JP-B" as used herein means an "examined Japanese patent puplication), JP-B-39-17702, JP-B-43-13482, JP-B-45-5331, U.S. Pat. Nos. 237,600, 2,763,625, 2,772,166, 2,852,386, 2,853,457, 3,397,988, 3,411,911 and 3,411,912. The techniques described in the specifications of these patents are based on the description of J. Q. Umberger, et al., Photo. Sci. and Eng., pages 69 to 73 (1957).
The problem of change in the dimension of the silver halide photographic materials caused by change of humidity and temperature can be improved by the above techniques.
However, change in the dimension of the silver halide photographic materials caused by the development thereof cannot be prevented by these techniques. The phenomenon of the change in the dimension of the materials caused by development is a serious problem in the use of the photographic materials, because the dimension of the photographic materials during exposure are different from those after development.
A method using a vinyl chloride undercoat is disclosed in Japanese Patent Application No. 62-94133 to improve dimensional stability during development. However, the problem of dimensional change caused by development cannot be satisfactorily solved by this method, and a method for solving the problem is required.
When the polymer latex is incorporated in the hydrophilic colloid layer as described above, the polymer latex often has an adverse effect on film strength, wear resistance and the adhesion of the layer to the support in developing solutions.
Methods for solving the problem of the adverse effect of the polymer latex by using polymers having an active methylene group capable of reacting with conventional gelatin hardening agents are disclosed in U.S. Pat. Nos. 3,459,790, 3,488,708, 3,554,987, 3,700,456 and 3,939,130, U.K. Patent No. 1,491,701. Dimensional stability in the developing solutions could be somewhat improved by these methods without detriment to film strength and wear resistance. However, a further improvement in dimensional stability is highly demanded in the field of multi-color printing or printing which must reproduce accurate line drawings. No. JP-A-60-3627 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") discloses a method for improving dimensional stability by using a support prepared by coating both sides of a polyester film with a polyolefin. However, this method is of no practical use.
As methods for obtaining high-contrast photographic properties, methods using hydrazine derivatives are disclosed in U.S. Pat. Nos. 4,224,401, 4,168,977, 4,166,742, 4,311,781, 4,272,606, 4,211,857 and 4,243,739.
According to these methods, there can be obtained photographic materials having super-high contrast and high sensitivity. However, when a large amount of the polymer latex is used for the purpose of improving dimensional stability, it has an adverse effect on photographic characteristics. For example, the function of the hydrazine derivatives to obtain high contrast is inhibited and as a result, high contrast photographic characteristics cannot be obtained Thus, there is the disadvantage hat the amount of the polymer latex to be used is limited and hence satisfactory dimensional stability cannot be obtained
The ratio of the expansion of unprocessed films and processed films due to change in humidity can be reduced by specifying the ratio of the thickness of the hydrophilic colloid layer to that of the support. However, the dimensional stability of photographic films before and after processing stages (e.g., development fixing, water washing, drying) cannot be improved, because the support is elongated by water absorption during these processing stages and not restored to its original state after drying and it takes a long time until it is restored to its original form. Hence, the support in practice remains elongated. When the length of the unprocessed film is compared with that of the processed film, the latter often remains elongated. Accordingly, dimensional stability is deteriorated by processing including development and this is a serious problem in the field of printing photographic materials.
Though the ratio of the expansion of the film due to the change of humidity can be reduced by incorporating the polymer latex in the hydrophilic colloid layer, the above-described problem cannot be solved, because processing solutions penetrate into the support during the processing stages.
Japanese Patent Application No. 62-94133 discloses polyester supports coated with vinylidene chloride copolymers to solve the above-described problem. This technique is a excellent to improve the change of dimensional stability caused by the processing of the printing photographic materials. However when the support is coated with the vinylidene chloride copolymer, a coated film having a uniform thickness can scarcely be obtained There are problems that the coating is uneven and adhesion between the support and binders becomes poor. An effective method for solving the problems has not been found.
Further, when the vinylidene chloride copolymer is coated, a high shearing force is often applied to a gap between a coated surface and a coater or to the back-flow valves of feed pumps for feeding coating solutions. Thus, there are problems that the polymer is agglomerated, the coated surface is deteriorated and production units must be cleaned.